The packaging of MEMS components is used, on the one hand, for the mechanical protection of the chip. On the other hand, the packaging allows the mechanical and electrical incorporation of the component within the scope of the second-level assembly, for example, on a printed circuit board. Packages or ceramic housings based on printed circuit boards are typically used in practice as the packaging for MEMS components. Both packaging concepts are associated with a relatively high manufacturing expenditure. In addition, the conventional packages are relatively large in comparison to the chip size.
German Patent Application No. 10 2010 040 370.9 describes a wafer-level-based packaging concept for MEMS microphone components. According to one form of implementation of this packaging concept, the front side of the MEMS microphone component, in which the microphone diaphragm is implemented, is provided with a cap wafer. It functions as an interposer for the second-level assembly and is therefore provided with electrical through contacts, via which the MEMS microphone component is electrically contactable.
The package is thus implemented here in the form of a wafer stack, the diaphragm structure and optionally an integrated electrical circuit of the micromechanical microphone chip being protected by the interposer. This package may be assembled and electrically contacted using standard methods. A special advantage of this packaging variant is that not only are the micromechanical and circuitry functionality of the microphone chip and the structure and electrical functionality of the interposer applied and produced in the wafer composite, but rather also the connection of microphone chip and interposer is manufactured in the wafer composite. The packages are only separated thereafter. This very extensive parallelization of chip manufacturing and packaging is extraordinarily efficient, which affects the manufacturing process and the manufacturing costs. In addition, the component size may thus be reduced to a minimum. Such packages require extraordinarily little printed circuit board space and have a very small overall height. This miniaturization both in area and also in height opens up manifold options for the development of novel and improved final products having microphone function.
The introduction of sound occurs in the package described in German Patent Application No. 10 2010 040 370.9 via a passage aperture in the interposer, whose aperture area generally corresponds to the diaphragm area of the MEMS microphone component.
This layout of the interposer has the effect that only a very limited area is available for the connection contacts of the second-level assembly on the assembly side of the package, i.e., on the surface of the interposer facing away from the MEMS microphone component. The larger the passage aperture in the interposer, the greater the risk that the sensitive diaphragm structure of the MEMS microphone component will additionally be contaminated or damaged during and after the second-level assembly.